A new method for extended target radial velocity estimation was presented for high pulse-repetition -frequency (PRF) up-down stepped-frequency (SF) linear frequency-modulated (LFM) pulse radar with hypersonic missile-borne application. This method firstly achieves the ambiguous estimation of target radial velocity by the range difference caused by range-Doppler coupling between range profile segment of up frame and down frame, then achieves unambiguous estimation by using quadratic phase term compensated and velocity matched correlation between the range profile segment of the two frames. Theoretical analysis and simulation results have shown that this method has the advantages of wider range of unambiguous velocity measurement and less computation in velocity searching and matching, compared with the traditional methods.